fiberglass loose fill
Glass fibers stuffed loosely into wall or roof cavities for thermal insulation.
Fiberglass loose fill insulation consists of unbound masses of glass fibers stuffed or packed into cavities or open layers in walls or roofs for thermal insulation. If the fibers are bound together in any kind of sheet or mat, then they are not considered loose fill.
The glass fibers remain unbound within the insulated cavity or open layer. A bagged, sheet-like, or matted product is a different insulation form.
The usage identifies both the glass-fiber material and its loose arrangement. Mineral-wool loose fill has a similar fibrous form but a different raw material.
